1. Field of the Invention
The invention relates to a device for reversing the steering movement of a steering-wheel shaft of a vehicle.
2. Description of the Related Art
Tracked vehicles having track chains, especially rapid tracked vehicles, are usually steered by active steering systems in which further drive movements are superimposed on the main drive movements of the track chains. During forward travel, the superimposed rotational direction of the further drive movements for executing a left turn is oriented forwards on the right-hand chain and is oriented backwards on the left-hand chain.
During travel in the reverse direction, the superimposed rotational directions remain identical without further devices, with the result that the travelled track is reversed. That is to say, unlike in the case of passenger cars or trucks, the vehicle would maintain its rotational direction.
As tracked vehicles make up only a negligibly small percentage of all vehicles, there is often the wish for a tracked vehicle to react in exactly the same way as a wheeled vehicle, that is to say to retain the same track during reverse travel in turns as in forward travel.
DE 38 19 446 C2 discloses an apparatus for switching over steering mechanisms. According to this reference, the superimposed rotational direction of the steering movement of the steering-wheel shaft may be reversed when the direction of travel is changed. A gear wheel which is connected to the steering-wheel shaft drives a forward pinion and a reverse pinion in opposing directions. The forward or reverse pinion can be brought into engagement alternately via a pivoting mechanism with a toothing system on an adjusting element for changeover purposes. The adjusting element is deflected in different directions by the forward pinion and the reverse pinion with the same rotation of the steering wheel and actuates the steering mechanism of the vehicle with the appropriate movement. It is possible to switch over only in the straight-ahead position of the steering system. For this purpose, the pivoting mechanism is locked in its respective switching position by a locking element. In the center position of the steering system, which is set during straight-ahead travel, the locking element can enter a depression on the adjusting element and thus releases the pivoting mechanism for a switchover process.
The disadvantage of this arrangement lies in the electric or hydraulic actuation of the system. Switchover while driving is not prevented if the electric and/or hydraulic changeover system fails.
Furthermore, the vehicle is not prevented from starting to roll counter to the selected driving direction, and thus the incorrectly actuated steering direction is not prevented.